Competitive binding of maltodextrin and pectin at the interface of whey protein hydrolyzate-based fish oil emulsion under high temperature sterilization: Effects on storage stability and in vitro digestion

Whey protein hydrolysate (WPH), maltodextrin (MD), low methoxy pectin (LMP) and high methoxy pectin (HMP) were used to study the interface binding under high temperature sterilization conditions (121 °C, 15 min). The effect of competitive binding of MD and pectin with interface protein on the storage stability and gastrointestinal fate of fish oil emulsion was studied. The low-molecular-weight MD and the interface protein undergo a wide range of covalent binding through the Maillard reaction, while a small amount of high-molecular-weight pectin can form a protective shell with the interface protein through electrostatic interaction to inhibit the covalent reaction of MD, which was called competitive binding. However, due to the bridging and depletion flocculation of pectin, the emulsification stability of fish oil emulsion reduced. After 13 days of storage, compared with the particle size of the WPH fish oil emulsion (459.18 nm), the fish oil emulsion added with LMP and HMP reached 693.58 nm and 838.54 nm, respectively. In vitro digestion proved that WPH fish oil emulsion flocculated rapidly in the stomach (1.76 μm), while WPH-MD and WPH-MD-pectin fish oil emulsions flocculated slightly (less than800 nm). WPH-MD-pectin delayed digestion in the gastrointestinal tract, and HMP exhibited a better slow-release effect. This study provides reference for the design of multi-component functional drinks and other bioactive ingredient delivery system.